The invention relates to a sensor for in-vivo measurements. A sensor of this type is known from U.S. Pat. No. 5,390,671. Sensors of this type enable electrochemical measurement of analytes in a human or animal body, for example of glucose or lactate. For this purpose, an electrode system, which is arranged on a distal region of a substrate that is provided as a sensor shaft, is introduced into the body of a patient such that a transcutaneous measurement can be carried out by electrochemical means. This process is commonly called insertion of the sensor. Usually, the sensor shaft is punctured into the body of a patient by means of a slit cannula that can be pulled out of the body of the patient after the insertion is effected such that the sensor shaft bearing the electrodes remains in the body of the patient. After the insertion, a proximal region of the substrate projects from the body and forms a sensor head for connection of the sensor to a measuring device. The sensor head bears metallized surfaces with contact fields and is usually provided in the form of a plug-in part such that a coupling or socket with a matching slit can be plugged onto the plug-in part to allow the sensor to be connected to a measuring or analytical device. In this context, the arrangement of the contact fields defines the plugging direction in which a plug connector is plugged onto the sensor head in order to connect the sensor.
Like all medical devices, sensors for in-vivo measurement must meet the highest requirements with regard to their reliability. Moreover, the sensors should be as easy to handle as possible such that they can also be used by medical laymen in an ideal case. Moreover, the use of a sensor should be associated with as little pain for the patient as possible.